We are investigating the structural and functional organization of the eukaryotic genome, especially with respect to epigenetic systems responsible for cell differentiation and carcinogenesis, by studying: a) the evolution of the primary structure and the tissue-specific variation of the nonallelic histone variants and minor histone species resolved by polyacrylamide gel electrophoresis in presence of nonionic detergents; b) the properties of histone complexes containing different variants and minor species; c) the nature and distribution of proteins tightly bound to DNA by nonionic forces; d) the changes in tightly bound chromosomal proteins associated with cell differentiation and leukemic transformation of different bone marrow cells.